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6qq4gy | How is the time relative ? | Whoo boy, this is tough to explain simply, but I'll do my best.
Suppose you threw a ball at 50 mph to your friend. To both of you, standing still, the ball is traveling 50 mph. But suppose you were riding in a car down the road at 20 mph, and you threw the ball at your friend standing in front of the car. In that case, you'd throw the ball at what you see as 50 mph. But since your friend is standing on the ground, it looks like the ball is traveling 70 mph, because the car's speed is added. So far, so good, right?
Everything changes with light. You can't do that sort of velocity addition to the speed of light. If instead of a ball, you were shining a light, both you and your friend would see that light traveling at EXACTLY the speed of light, not the speed of light plus 20 mph.
The only way this can possibly work is if time warps or bends to accommodate things traveling at or near the speed of light. As a result, you and your friend experience time slightly differently when you're traveling at different speeds. This doesn't become appreciable until you start hitting significant fractions of the speed of light, or unless you're measuring that time very precisely.
Two examples for some perspective. The cosmonaut Gennady Padalka has the world record for longest time spent in space. Since being in space typically means being in orbit, and being in orbit means traveling very fast, he is the human most strongly subjected to time dilation. His 879 days in space (traveling at a constant 17,000 mph) have put him at around 2-3 seconds of total dilation, meaning he is literally 3 seconds younger than he would be if he had never gone into space.
The second example is one of the ways we confirmed the theory of relativity. The GPS system is dependent upon a series of satellites in orbit around the earth, and the satellites depend on very accurate atomic clocks in order to function properly. When doing the initial calibration of those clocks, the engineers forgot to account for the relativistic effects of traveling at orbital speeds, and the GPS system didn't work. Once they adjusted for the clock's orbital velocity, everything lined up much better. | 28a2b5e5-246a-42a1-a422-bef16487e2d3 |
50eirp | Why does standing in one place for twenty minutes make my feet hurt more than walking for an hour? | Standing up straight still requires your muscles to do work. But it's "static' work which means it's the exact same muscles doing the exact same thing over and over again *without being given a chance to relax and recover*
When you are walking around you are using a series of difference muscles. Even though there may only be a short gap between when each muscle gets used it's still enough to spread the load and give your muscles (some) time to recover. | 186e96b8-b1fb-46b2-a472-2d0b63c40b26 |
80nhbk | why are some banks able to give different rates on things, ie. a higher yield percentage on savings accounts, as opposed to others? | Like any business, it's competition. There are certainly costs involved with running 1000's of branches that online banks don't have to deal with, so they do have some efficiencies they can pass along.
But there are also concerns about online-only banks many consumers have, and higher rates are a way to entice more people to consider using them. Even if the expenses were equal, the online banks might be willing to forego profits today to grow their customer base, effectively using the higher rates as a marketing expense for customer acquisition. | 65fa4d22-38b4-4dde-becd-b1e1fcca90ca |
1o6ay1 | Why aren't birds electrocuted when they stand on power lines? | Electricity wants to take the easiest way to the ground (earth) the wires that are used for the power lines have low resistance, meaning it is easy for the electricity to travel through it. whereas a bird has a high resistance so it is hard for the electricity to travel through it. therefore almost all the electricity will travel through the wire, and almost none would go through the bird.
If the bird were really long and touched the ground as well as the cable, it would travel through the bird as it is the easiest way for it to get to the ground so the bird would be fried. | 902ede3b-d031-4312-8686-b70d0cde1f96 |
33n182 | Why chickens are not protective of their eggs like other birds? | I grew up on a small farm. We always had laying hens. So I can tell you from experience that you are mistaken completely.
It varies between chicken breeds. Some breeds of chickens are "broody." Meaning they do a good job of laying eggs and taking care of them until they hatch. Broody hens will peck and claw you to the point of drawing blood if you mess with the eggs or chicks. Others are not, because they have been bred to a point where they just don't give a shit. They will lay eggs and ignore them afterwards.
We used to use a golf ball to try to encourage hens to lay in a particular spot because they'll think it's another egg and adopt it and lay more. I've ended up with bloody knuckles checking to see if a hen was laying only to discover she just tried to take on a predator 100X her size to protect a ratty old golf ball.
tl;dr: depends on the breed of chicken
edit: spelling | 796fb5ab-2860-463b-af39-e12b331b4b32 |
3g5hne | Why is it that each month, our country adds "250,000 jobs", but unemployment seems to remain the same? | The real answer (rather than the other person's flippant response about new people being created) is that the official unemployment rate has long been deflated because it doesn't include people who have looked for a job for so long and not had any success that they have given up. Those people are considered to be "not in the work force" and are therefore not "unemployed and looking for a job", which is what the unemployment rate measures. As economic conditions improve and more people find jobs, those people who gave up are reentering the workforce at approximately the same rate, making the unemployment rate change slowly if at all. | 685ea255-b3f7-436e-a976-dfc0a10d18a6 |
1fdet4 | What really happens when you get a blown motor? | That could mean a lot of different things. The timing belt could have snapped, causing the pistons to hit the valves. A connecting rod may have broken due to a spun bearing, punching a hole into the block as a result. Blown really just means irreparable damage, but it doesn't tell you what broke. And if it's an older car, a mechanic may also tell you the engine is blown when the damage is technically repairable but it's cheaper to buy get a used a remanufactured one. | 198e4cfc-7917-46c1-b5a6-d9a425f61229 |
33r53b | when the Fukushima nuclear power plant lost power which led to much of its problems, why couldn't things be powered by the reactors themselves? | As another commenter said, the reactors automatically shut down due to their seismic sensors triggering the reactor protection system. Japan's nuclear plants automatically scram on high seismic activity to ensure the control rods don't jam up on the way in.
However, even if the reactors didn't scram, most nuclear units including the General Electric BWRs at Fukushima cannot operate their generators without the power grid, and cannot operate without enough loads to take their power.
The first issue is called a load reject. Most reactors are not designed to stay online and keep producing electricity without the power grid. If the grid goes away, the generator needs to reduce its power output to less than 10% in a few hundred milliseconds to prevent itself from overspeeding and damaging itself. Because of this, most large/nuclear generators automatically shut off. This triggers a reactor scram in most plants as well, because the reactor has no place to send its steam to, and it can have an over pressure/overpower condition.
The second issue is that large generators and turbines are not stable at low power levels. Monoblock turbine rotors in particular start to have dangerous vibrations if they are below 20% power for too long. It takes a different design of turbine and generator to properly run without the power grid to stabilize it at low loads.
The third major issue, even if they could supply their own power, all of the on site power busses and circuit breakers were underwater and damaged. No way to get power where it needed to.
All that said, all Fukushima units had at least two steam powered cooling systems. Unit 1's systems weren't running (the isolation condenser was manually switched off to prevent excessive cooldown rates in the reactor) when the tsunami hit, and the valves for unit 1's systems failed in such a way that they could not be restarted manually. Unit 2's steam driven RCIC/aux feed pump ran for 70 hours before failing (it's only designed to run for 4-8 hours during blackout scenarios). Unit 1 and 2's high pressure coolant injection systems could not function because they didn't have battery power. Unit 3's RCIC and HPCI (high pressure coolant injection) ran for a total of 32 hours. RCIC probably could have run longer, but Japan's emergency procedures did not have them disable all the RCIC safety interlocks and make it run to failure. It shut off on a safety interlock which really shouldn't be active for emergencies.
I'm a nuclear engineer. | 2cad7554-dcd9-49b0-8452-4543e96236e5 |
558344 | Why is it in their nature for some animals to be so loyal and friendly towards humans while other animals despise us and are not friendly or loyal? | Generally the animals that are loyal and friendly have been bred and conditioned to be exactly that.
Take dogs. We have spend thousands of years breeding them. We have selected certain traits that we enjoyed and bred them for that reason. Loyalty and friendliness were some of those reasons. And it is in the dog's best interest to be friendly too, cause dogs that aren't friendly or trustworthy are generally not fed and even put down. Then we take that natural inclination towards friendliness and loyalty and further compound it by teaching pups from the very start what behaviour we want them to have and what behaviours are bad.
However that tiger you meet in the wild? He wasn't bred to be friendly. It isn't in his best interest to be friendly. | 8cc47e97-7e4b-4baf-b1d6-fac08b661291 |
22g61i | How do people become right handed or left handed? | I think it's still unknown. Scientists had a theory that it had to do with left or right brain dominance. But now it's pointing more towards genes.
It is weird though. I'm right handed with writing, but left handed in sports (hockey, baseball, golf). | c879f3e0-1d3a-4c92-b230-9e29b1781fe9 |
yetku | How does a company like _URL_0_ work? | Why are people asking the same questions from yesterday? | 1f250c92-3a71-4a46-95a5-7ca2ddd5257e |
5e9s6a | Why and how does sex appeal change over time? | It's a combination of cultural and biological factors. Obviously its typical and instinctual to be attracted to the opposite sex and certain features that indicate health/child-rearing ability and the like. However, if you particularly like something or especially associate it with sex, either accidentally or because society associates them together, then you may find it sexually attractive in a kind of pavlovian way. Heels might be a good example of something a lot of people typically don't find sexy until it's associated with women (or whatever else they already find sexy). Some people with poor social skills may find they don't enjoy humans at all and be sexually attracted to inanimate objects such as cars or trains, because they DO enjoy those things and we're raised to associate pleasure with sexuality (either implicity or explicity) -- truly, there are some interesting documentaries out there about people in extreme cases, fucking their cars and the like. People can be attracted to pretty much anything for the vaguest reasons between biological triggers and sexual association and pure chance. It is almost wholly subconscious and out of your control though. | bc05a56f-b356-4164-8ee4-01e5ad1273f2 |
16tpkn | What do lobbyists do, and why are they bad? | They are paid to argue for a particular interest. They get face time with various congressmen and committees pushing their employers agenda. The problem is that their agenda may not be aligned with what is actually best for the people. | f9bc271c-075f-47b4-91ef-b5592d3c2ab7 |
5famme | the difference between the Roman Empire, the Byzantine Empire and the Ottoman Empire | Byzantine Empire = Eastern Roman Empire
> How far off am I in this reasoning?
Rather badly. The East-West divide occurred in 313 AD; in 295 AD as a result of vast rebellions the original Empire was split between four rulers, two caesars and two augusts; by 295 the Caesar-august split was eliminated, leaving two different emperors. The two parts of the empire grew culturally distinct, and the Western half got quickly taken over by barbarians. Those barbarians are, by and large, modern Europe; Russia claims cultural, religious and dynastical (via Vladimir II Monomakh) succession to Byzantium; that's how "caesar" morphed into "tsar".
The Ottomans were a whole different lot: they conquered the former Byzantine Empire; they were a Islamist caliphate, launching jihads on Europe and enslaving foreigners in the name of Allah. There was no ethnic or cultural connection with the Greco-Roman civilization.
A missing key link is the *original* Islamic Caliphate that sprung from Prophet Muhammad's initial conquests. While Europe descended into the Dark Ages, the early Muslims conquered the entirety of Northern Africa and much of Spain, along with much of the Near East - embroiled in bitter wars with the Byzantine Empire. So, by the time the Ottomans rose, they were simply integrating splinter groups of the original caliphate, while also succeeding in taking over the city of Byzantium/Constantinople proper - thanks in part to the Empire having been ravaged by some of the later Crusades. Yes, the Crusades were supposed to target Palestine, but by then there were Crusades in the Baltics, and by the Third Crusade, Byzantine lands were also targeted for conquest. | d43799fa-77bf-4df6-baef-2537fd258ef1 |
206isp | What does the term "graphics" actually mean, and is it video-game specific? My friend always says animated movies have good "graphics" and I feel like there's a difference and she's using the wrong word. | Graphics basically means "visual images on a surface". A movie can have good graphics, a video game can have good graphics, etc. Computer graphics are a specific type of visual image, i.e., images created by a computer.
Colloquially, however, people tend to refer to computer graphics used in movies as "CGI" (Computer Generated Imagery) or effects (as in special effects), probably because those terms are commonplace in the industry itself. So, people talk about the "great CGI" or "awesome effects" in Avatar but rarely the "totally sweet graphics", even though the usage is correct. | 44404b0f-178a-4087-b05b-366a5941ff19 |
2dpex6 | How those little baby doll toy bottles work where you hold it upside down and the liquid seems to appear like he drank it, but when you hold it right side up, it refills...? | The bottle is actually two containers (one inside the other). There is a thin gap between the two which is filled with liquid.
This allows a very small amount of liquid to appear to fill the entire bottle. When you tip it, the liquid flows through the gap and down into a resevoir in the top, making it appear empty. | 37d2f8d1-c603-434b-963d-a8296b91d847 |
oh2if | Why does (fire) cooked food taste better than raw food (mostly)? | > Is it an evolutionary thing so that we cook our food more?
Evolution works in a kind of after the fact way. Those who cooked more survived better and thus reproduced more. | 76bafffc-6ec3-445f-bc3e-94497dcd0de6 |
1s2c0e | Why do we only have Black Friday sales once a year? Why can't we have the deals all year long? | Some stores tried this. They found that they sell more if they have higher prices then drop them shortly for a sale than if they keep the sale-low prices all year.
People just really like sales. | a5507b53-5118-4f5a-8c6c-f6663a408b00 |
39694q | how to birds fly so in sync in a flock? | I don't have sources, but I have heard a few explanations. First, they make the decision to move in any one direction based on a sort of democratic system. One bird might tilt its tail or wings a certain way, and that is its 'vote'. When a majority of the birds in the vicinity agree on which direction to move, they all shift in unison. Then, birds further away in the flock have a 'chorus line' reaction. Much like a woman in a chorus line sees a leg kick up down the line and anticipates her own kick, birds see others changing direction and do so in a sort of wave. | 00e9284d-cc55-41ad-afee-47504c97d16d |
23mbu8 | Why do I nod along with characters in movies? | Because this is asking about a condition you suffer it qualifies as a personal problem according to the sidebar rules.
I'm not sure what, if any, subreddit would be better for you, but if you find one that works for you, let me know and I'll edit it into this template so anyone in the future will know, too!
Good luck! | d1e7fcc1-4fae-45bc-a0a8-2d4f631d109b |
4rwfh8 | Dogs have a fear of heights because it knows it can die if it fell off. If someone was with a dog and jumped off a high ledge, would the dog consciously know the person was going to die? | One thing I'd caution, while fear of heights is not necessarily a hardwired instinct, that does not, by that same token, mean that having a fear of heights actually equates to an understanding that you can die if you fall off.
Studies with babies, for instance, suggest that they come to fear heights as their experience with movement increases, and they become better able to process how their body interacts with the environment, and increase their dependence on visual information. This does not mean, however, that they know "this fall can kill me." In fact, there's not necessarily a relationship at all between "I've experienced falling and it hurts" and "I'm afraid of heights." Even babies that don't fall gain this avoidance.
Rather, as they come to rely on visual information, and come to a drop off, the information provided flatlines. There's no surface to orient against. "How will my body work here?" "No data" that seems to provoke wariness. | 7750a7d0-1eb2-4652-8668-a1f18302afed |
1ozbs7 | why do some cans get cold when shaken. | Its not actually getting colder, it just feels like its getting colder. When the can isn't shaken, heat is transferring between the liquid content of the can and your hand by conduction. When you shake the can, the liquid starts moving, and introduces heat transfer by convection. Convection has a much higher rate of heat transfer than conduction, and so when you shake the can you are transferring heat from your hand to the liquid at a much higher rate. This increased rate of heat transfer from your hand to the can is why you feel it getting colder, even though the contents would actually be warming up, because you are performing work on the can and inputting energy into it in the form of heat. | b7719edd-219a-485a-adea-df14b0260fc5 |
2mqdw4 | Why do pregnant women with Ebola have a 95% chance of dying, (rather than the 40% chance of dying)? | During pregnancy, the immune system is suppressed to prevent the woman from rejecting the fetus. This makes fighting virulent infections a bit difficult. This is also why many women with autoimmune conditions experience remission during pregnancy. | 3c22233c-6949-448c-ac3d-2a48879a40c2 |
32oxws | What will realistically happen in 20-30 years when the babyboom generation dies and their wealth is inherited/re-distributed? | You're making a lot of assumptions not necessarily tied to facts. You're assuming that a decent portion of that 4-10 trillion dollars are liquid assets just sitting in an account somewhere not being spent. A gigantic portion of that is guaranteed to be real estate and property that will simply be passed on as is.
In addition, a huge portion of that is going to spent on nursing homes or medical care as they age, so it will go into the economy in a slower rate that way as well.
In short, it's not as if there's going to be a 10 trillion dollar tidal wave of cash dropping on the younger generations. | b93fa348-b0e7-43b2-8cfe-33c0ffc3afa8 |
7xu7xh | Why does warm air rise? | Density.
Warm air has more energy in each particle which means it expands in volume. Equal mass but a higher volume means lower density. Hence,, they rise.
Similarly, cold air has less energy per particle and tend to stick closer to each another. Equal mass with lower volume means high density. | bf897ca3-ce3f-4864-8655-d11dd37e9764 |
2atiq3 | Why do I wake up tired after I've slept in? | If you wake up during the wrong stage of sleep you can feel extremely tired. This is why if you get up after your body wakes up normally you usually don't feel too exhasted, but getting woken up from an alarm can leave you devastatingly tired.
This is just one possibility though, there are many others. | 22dd160c-25e4-480a-87b9-067f86d77c71 |
3xrne3 | How will planting a wall of trees across Africa stop the spread of the Sahara desert? | One thing that can lead to desertification is the loss of plant roots that hold soil in place and make it better at retaining moisture. Part of the hope is that the trees will help hold and enrich the soil while also providing some measure of wind break to decrease the extent to which to soil is stripped away. | 697d1f2d-f967-4996-a3ba-1368c1194aeb |
8oafiw | Do insects get hot from the sun? If so how do they cool down? | insects are cold blooded, so they generally prefer hot environments to colder ones. This is why there's suddenly millions of them around as spring turns into summer, and why most die off or 'hibernate' (not the technically accurate term, I know) through the winter.
In extreme heat conditions lots of insects have tricks they can use to survive; lots of them become more nocturnal, some can harden their exoskeleton to retain more water, etc. | c818b934-6140-4d51-883b-ac6b40bfefb1 |
3m8ru5 | Why do tennis balls come in a sealed container? | The rubber that tennis balls are made of tends to dry out, stiffen, become brittle and less bouncy if they are left out too long. "Fresh" tennis balls bounce better, and are thus preferred for actual tennis play. If you're just buying them to play fetch with your dog it doesn't matter too much. | a6d142f3-4cd2-46f5-b131-cb0f693b96f3 |
3tkfcc | How is tax exemption for religious businesses such as churches not a violation of separation of church and state? | Non-profits are tax exempt, because most churches are run as non-profits, they don't pay taxes. It has nothing to do with the fact that they are religious institutions. | e4d2a925-e728-444b-887f-1ae7e7a95f08 |
46klor | Why does breathing stop being a natural thing after we think about it | There is a part of our brain that controls heart beat, digestion muscles, everything we can't stop, is controlled by that part of our brain.
He also controls blinking, breathing, and all things you don't have to control, but can choose to.
Those functions have an override 'switch' that you can pull by thinking about it. This lets you close your eyes when you want to, or hold your breath before going under water.
But as soon as we stop thinking about it, it goes right back to automatic. | 9475b46b-c046-4e08-9c34-b2580fed6f35 |
2fe8p1 | Why can I be starving when going to sleep and not feel hungry at all when I wake up ? | Fasting State. When you're not actively digesting foods your liver regulates your blood sugar by exporting glucose into the bloodstream based on the amount of insulin in the blood. So you wake up with the hunger response sated and you don't feel hungry until you burn up that blood sugar.
_URL_0_ | da3dfe6c-7c53-4338-aa55-b80668eb29a3 |
kt2ii | The Bohemian Grove club? | Rich and powerful people drink a special juice that makes them happy then they dance in front of a giant owl statue in the forest. | b0df96f6-e943-43e7-b353-8c6cafb616ab |
87q9n9 | Why do most people sleep better when it rains / thunderstorms ? | I can't say I know for certain, but I'm guessing it has something to do with it being a calming noise to some.
Eg. Waves on the ocean, raindrops, piano.
I definitely sleep better when it's raining, so there's that. | e2046a99-2472-4c5a-bcbe-7c87968a0bda |
34yvem | How did Mexico defeat France when they were clearly outnumbered? | At the battle of Puebla? The French weren't ready for a fight, and the Mexicans were. They had made much better defensive preparations than the French forces expected, so the French attacked expecting an easy victory and weren't able to react when they met stiff resistance. | f54dbbff-15c9-48f7-8243-79080d2f6d23 |
1s7ipi | The speed of light and relativity | I think you are missing a key part of the theorem of relativity here. That is: **the speed of light is the same for ALL observers**. So, no matter how fast you are moving the velocity of light is still *c* (300,000 kps).
So lets consider your example:
> if you had a flashlight and a rock, and the flashlight was moving at 200k kps relative to the rock, and the flashlight was turned on
Your conclusion is actually wrong, nobody will observe the light to travel at 100k kps. In this case a person riding on the flash light would see the light traveling away from the flashlight at *c*. A person sitting on the rock would also see light traveling away from the flashlight at *c*. Light travels at the same speed for ALL observers.
Now I imagine that you are asking, how can this be??!?! And the answer is where we get into the mindfuck of relativity.
For this situation to happen (and as far as we know this **is** what happens in the real world) both people must measure light's velocity to be 300,000 *kilometers per second*. This is possible because space and time it relative to each person. 1 second for the person on the flashlight is NOT equal to 1 second for the person on the rock. Also 1 metre as measure by the person on the flashlight is NOT equal to one metre as measured by the person on the rock.
Even thought they are moving with respect to each other they both measure 300,000 Kilometers per second, *because time and space is different for each of them*.
.....
Let that sink in a bit.
.....
Ok, so to reiterate: time and space (seconds and metres) are relative to the frame of reference you are in. But the speed of light is constant for all frames of reference.
PS. Lastly, in regards to light 'slowing down' this only happens when light travels through a medium, for example air, or glass. But a beam of light traveling through glass has the same velocity *for all observers* no matter how fast they are moving compared to the glass. | d1de58ac-c487-4522-8cd6-4e3f6fa14f54 |
427lfx | How are these new chipped credit/debit cards offering more security when cashiers do not prompt us to enter a PIN, signature, or show ID? | While that is the case, most identity theft doesn't happen with your actual card. It happens when they get the card numbers. If you had your actual card stolen, you'd report that as soon as it happened. People using your card numbers isn't noticed until you see it on your bill. | 90092f0c-18ca-4b3e-af11-0f0afb22b493 |
2zb1ku | Why/when did tea begin to lose its popularity in America? | Have you never stepped foot in the South? We drink gallons of sweet tea a day. | 9d61bc17-0b35-46ee-86f3-7db5bf7f4723 |
1ikk23 | Why doesn't water burn? | So, "burning" is combining something with oxygen (or some sort of "oxidizing agent"), such that the final result is more chemically stable than what you started with.
Now, I used a lot of potentially confusing terminology there. An oxidizing agent (of which oxygen is the main example, hence the name) is simply a chemical or element that becomes more stable if it has extra electrons. Think of it as kind of the same as a magnet, which is "more stable" when it's attached to a bunch of metal. If you take a magnet and put it in a pile of iron filings, it'll pick up a bunch of them, but will eventually reach a point where it has so much iron stuck to it that it can't pick up any more. An oxidizing agent is like that, but with electricity instead of magnetism. It greedily accepts electrons . . . up to a point.
So now, imagine burning hydrogen. What you're really doing is combining hydrogen with oxygen in the air, which creates a new compound -- water -- that is more stable than either hydrogen or oxygen alone. The oxygen pulls electrons from the hydrogen kind of like a magnet with iron flings, but once it has two electrons (one from two different hydrogen atoms), it becomes stable. In fact, water cannot be made any *more* stable by combining it with additional oxygen. If it could, then burning hydrogen would result in the hypothetical, more-stable end product instead of water.
**tl;dr:** You can't burn water for the same reason that you can't burn ashes: It's already been burnt. | 8101ec42-3d5e-41cb-b91f-1acb6f066fc1 |
21cnqn | Why do women enjoy sex even if they don't climax yet men are left relatively unsatisfied when they don't "finish the job"? | just think about what's actually necessary in order to reproduce. | 33cf2e57-8c40-4a19-9ae8-e62b55662d73 |
7vg169 | Why are there no (or few?) green mammals? | [From this](_URL_0_), it would seem that the reason that there are no naturally green mammals -- I'm not counting sloths, whose green pigmentation comes about from algae in their fur -- is because hair colour is determined by melanin. Melanin doesn't have a green form. In birds and lizards, the skin is capable of [scattering blue light](_URL_1_), which leaves a greenish or bluish colour that you don't often see in mammals. (Other species, especially invertebrates, are capable of producing blue or green pigmentation.)
Mammals never really benefited from vibrancy of colour in the same way that a lot of species did: to my knowledge there are no poisonous mammals, so that takes out the benefit of being brightly coloured as a warning in the way that tree frogs might be, and they tend not to have quite as much reliance on vivid colour for mating rituals in the way that, say, birds might. From an evolutionary perspective, mammals spent most of their time trying to go unnoticed and keep warm, which lends itself to brown fur. (There *are* [brightly-coloured mammal species](_URL_2_) -- mandrills and such -- but they seem to be recent evolutionary branches, at least on a lizard timeframe.) | f84564ff-d22f-4b68-aeb9-f4014e7706a3 |
24rjt7 | Why doesn't lightning kill all the fish in the ocean when it strikes? | Lightning like all electricity takes the easiest path to a ground. If it directly struck a fish it would kill it. Otherwise it follows the path of least resistance to the earth. | 3486614f-5363-4539-b005-50933b976911 |
2q157b | How do gameshows get the money to just give away day after day? | A top network show like *NCIS* is paying about $2 million in episode in actors' salaries alone. A premium cable show like *Game of Thrones* runs $6 million an episode.
Games shows are cheap by comparison...no actors, no writers, no car chases, just a single set, a washed up actor and a few bimbos. They do it all in one take, and can bang out a week's worth of episodes in an afternoon. If they give out $100,000 in prizes, they are still coming out way ahead. | ca9b8fce-2a6e-483c-a529-a31d9bd9be5c |
6ayw3a | Why does the body store unnecessary amounts of fat, to the point where humans can become morbidly obese? | You have to keep in mind that access to enough food to eat yourself to death is a fairly modern thing to have. Of the billions of years of life evolving that led to us, it's only in the last few thousand or so that this has been possible.
If you don't have access to this much food, "storing unnecessary amounts of fat" becomes "being able to eat more now and use it later."
Taking that into account, the ability to store dense reserves of energy (fat), which also happens to help keep you warm, is an extremely useful survival tool. In fact, it's postulated that this is one of the evolutionary advances we have over other apes: a gorilla or chimp that massively overate like a person can would just die from it. Being able to "stock up" internally is one of the abilities that allowed our ancestors to migrate through areas that didn't offer enough food. The only other mammals that can put on arbitrary amounts of fat like we can and not die from it are aquatic (which also happens to be another situation where food can be scarce for long periods of time and staying warm is important). Don't get me wrong: all mammals have fat stores, but humans can put on several times our normal weight in fat alone, and most mammals can't do this. | b9cddc12-1823-41a8-bd14-933ecedd976b |
2je722 | Why doesn't the military/police use full body, completely enclosed, bullet proof armor? | It's called a tank. They put wheels on it. It would be more expensive than you're worth. stupid heavy, slow. Every shooter is taught to shoot center mass. | c1d35ff7-692f-4c7f-916a-b26013e69355 |
3ivo0o | Why are so many lists on the internet slideshow format? | Because websites get paid for ads per impression, and every new page is a new set of impressions. So instead of having one page where there's one impression for each ad, having 20 pages gives more impressions, and more money for the website operator. | ef09d946-cd30-46a5-b6ab-a60a2326d92c |
kilm6 | - The East vs West Hip-Hop feud | This began a while ago, in the early 1990's.
Pretend there was a large african desert. In the desert, there are many different animals, but the strongest, and most powerful ones, were the Lions. The desert was kind of split into two, so you had the "Right side" and the "left side" . Each "side" had one very large, powerful lion. Every animal on each side respected both lions. But after a while, the animals on the right side decided that they liked the RIGHT lion the best, and started to say mean things about the left lion. The people on the left did the same thing, they really looked up to their lion, and thought he was better than the lion on the right, so they said mean things about the lion on the right. Eventually the two sides really started to hate eachother, and even though both the lion's knew it was wrong to hate your neighbours . they refused to just lay down and sort the stuff out. Then, one day, the lion from the right side was over in the left side of the desert, doing a dance for all the animals to see. When he was done the show, a big mean poacher came and shot him with a bow and aarow, and then the RIght side lion died. Soon after, the lion on the left was killed too.
In adult terms:
The "lion" on the right is "The Notorious B.I.G." , AKA "Biggie" , a famous hip hop artist from New york. The lion on the left was " Tupac Shakur" , an artist from California.
In the beginning of their careers, Biggie and Tupac were friends. They did shows together, recorded music together, toured together. They worked together, and did amazing things. Then, one night, Tupac was coming over to Biggies house, and when he was in the lobby of the building, some men jumped him and he got hurt badly, and hospitalized. He blamed it on Biggie, and said it was a set up. Biggie denyed the claims, saying he had noithing to do with it. Her tried to visit Pac in the hospital, but the hospital staff would not let him in. When all the hip hop fans from California gor word of this, they all automatically started a feud, hating the east coast , and eventually, these feelings were mutual.Tupac was later on killed. Then, a while later, after doing a show in California, biggie was killed by armed gunmen while driving back to his hotel from the show. The shooter was never discovered. | 3fd107a1-3105-40f5-8573-0dd6da71e0f9 |
30v3pz | How is possible to watch a video file whilst downloading it at the same time? | Let's compare this to an highway in a building-process:
On the start you've got the informations about the highway like the name and the length (data size or number of frames).
Now the construction workers (your computer/decoder) are getting the plans and the material (data) from somewhere (the server in this case). With this information they build the street kilometer per kilometer (frame per frame). Once one more kilometer is built you can actually drive on it (watch it). And because the contruction wrokers also know how long the highway is going to be, they know when to stop.
If the company supplying the materials and plans for the highway or the construction workers are too slow, you have to stop at the last finished kilometer (video is buffering).
So, it's possible because there's a data stream containing frame per frame. And hence you only need the latest frame and maybe some of the previous ones, you can show the latest fully downloaded frame. | 2fc9b974-71bc-40dd-92ec-3f9d4e5572cb |
la39m | Why does it feel so much better waking up after 8 hours of sleep at 9, rather than 7 or 5? | Your pineal gland releases melatonin when it is dark. This neurotransmitter tells your brain and body to regenerate. When you wake up while too much is still in your system, you feel bad because you are busy regenerating.
After 7, when the sun starts shining, your pineal gland will be releasing seratonin, the same stuff that gets triggered for release by MDMA / ecstasy. Thus you feel better at 9 when your system has more seratonin. | 27ec0e95-7bdb-4f80-aa39-a92d03f952e2 |
5gvlbm | Why sand/salt melts ice? | The sand is for traction, not so much to assist in melting. It helps cars grip the ice better.
Ice is used because it lowers the freezing point of water. Water normally freezes at 32f, while salted water can stay liquid at 0f. | 70d5c97e-acd9-45ae-a421-1b65df82f923 |
6eghou | Beep sound used for censorship | It's normally 1k tone, which is a standard for testing audio in broadcast. Basically it's used because broadcasters have always had it available.
Many times silence is used, but you notice it less. There may be rules in place that I am not aware of, but generally tone is used when the person's mouth is visible. 'Audio drops' are used when the mouth is not visible.
It is (usually) possible to adjust the level of the tone to match the dialogue, but it adds another step that no one (except the viewer apparently) cares about.
_URL_0_
_URL_1_ | 307d7f9a-0f1b-411c-bcc3-e957d6e221f5 |
3k2u7x | How does a plane crash into an ocean kill all people on board? | It is very difficult to land a plane even relatively safely on water. Especially when that water is rough or moving like the ocean is. So when an airplane, which is moving at a high rate of speed, attempts to land in the ocean, it will likely break up on impact. Many of those on board are often killed by the force of the impact alone. Others are knocked unconscious (which is a bad situation considering they are now being pulled under water) and others are injured and or disoriented all while trying to quickly find a way out of this massive aircraft that is sinking deeper into the ocean with each passing second. Believe it or not, crashing into the ocean offers those on an airplane a far smaller chance of survival than crashing on land because even when a plane loses all of its engines, the pilots still have a chance at landing an aircraft relatively safely as long as they can find a large enough area to do so on land. | 96df6d59-91b0-4c8a-a9a1-0ca3d39ee784 |
1vy6vb | How are dental records used to identify bodies? | Teeth are one of the toughest parts of the body and everybody's history is different. In cases where the body is badly damaged/disfigured teeth may be the only recognizable remains. | ef6140fb-7bcb-459c-9ec6-a2dc115d41c1 |
ymmh4 | Magnetic door locks. How do they work? | The magnet is a simple electromagnet. There is an iron block welded or bolted to the door on one side, and there's a mounted system with more iron bars on the frame of the door. When it's active, (you can't open the door) there is electricity going through the part mounted on the frame, which holds that part and the part on the door together. When you can open it, the electricity is off.
There's a switch on the inner jambar thingie (whatever they're called) which allows electricity from a unit that controls the magnet through. The controller senses that the bar has been pressed, and it deactivates the magnet. The same thing happens when you swipe your card or whatever method they have to deactivate it on the other side.
In the case of a fire, there's a place on the controller for the fire safety system to be wired in. When the alarm goes off, it is sending electricity to the controller like if someone was pushing the jambar or swiping their card, and it stays disabled until the fire safety system is turned off.
Source: I've taken them apart and hacked around with them several times. They're neat. | af3c831f-22bc-4b5f-b580-da0aba5b074b |
3r1p9m | In the event of mankind being wiped out (nuclear, asteroid, virus, zombies etc) what do the people aboard the ISS (and any manned spacecraft in orbit) do? | Die. Nothing else for it, it'll come sooner or later when they run out of the relevant resources needed to live.
There wouldn't be any specific plans for the crew to follow, and even if there were everybody on board would know it doesn't matter anymore if there's nothing else to do but choose how they die.
There's a firearm kept in the Soyuz capsule in case they land in a remote region after getting off-course. Meant to protect against wildlife that might get over-interested. It'd work just as well if anybody on board wanted to just end their life then and there.
You've also got the airlock, of course.
If you want to try and wait it out, see if maybe there is some hope sooner or later the atmosphere can't be kept breathable, the ISS relies on resupply ships to bring, among other things, oxygen. Sooner or later the food and water supply will fail. Even if you got over those, somehow, it's just a waiting game against something breaking you can't fix without a specialist and/or parts you don't have. | b438aa53-a298-46af-bc90-c098fc2b127e |
33hm1n | The aftermath of a sneeze. | Everyone gets the feeling, I don't know what causes it, probably something to do with blood pressure and heart rate stimulation | bef85099-bb0d-4f13-83bf-3fd354af71cd |
5m4m6v | Why do the Oscars award movies from the previous year? | They're held around the end of February. If they held Oscar's 2017, awarding only movies from 2017, they would only have two months of movies to award. Then, when February 2018 came around, they would miss the other 10 months of films of 2017 because they could only focus on films released in 2018 (a 2 month span) | 0457b09a-232b-468a-b272-587b61378485 |
ldu2k | When a car is moving on TV or a movie the wheels look like they're moving backwards... | If you take a picture of a clock every minute, then show the pictures in rapid succession, it will go from 12:00 to 12:01 to 12:02... and it'll look like it's going forward.
If you take a picture of a clock every 23 hours and 59 minutes, then show the pictures in rapid succession, it will go from 12:00 to 11:59 to 11:58... and it'll look like it's going backwards.
Motion picture cameras take pictures much faster than once a minute, but the same thing can apply. If the wheel is spinning at a speed where it rotates 90% of the way between frames, it will look like it's spinning backwards. | 8c656fb6-0518-47fe-93d6-f3382e7fcc51 |
1jf8xa | How did people originally translate languages? | By pointing at shit and saying what you called it. It's not a great technique fit explaining ennui, but for something like pig, it works just fine, and to be honest, in the days of 'first' most French people didn't know what ennui was.
Once you have the verbal language written is just teaching the person to right like you would a kid. | c10ab19c-2212-4a83-a6ac-a09e1549a5eb |
1mdi10 | Why are some people very light sleepers and will wake up at the drop of a pin, while other people are extremely heavy sleepers and can sleep through a brass band? Why aren't all adults roughly similar in their ability (or inability) to sleep through noises? | _URL_0_
Basically some peoples brains are just better at blocking out noise then others. | 71640e4d-27a9-440c-92ff-629f1afa0ab8 |
8loayt | What is the concept of a nation-state, and how is it different from pre-WW1 concepts of soveirgnty? | Before nation states, countries were mostly owned by dynasties (long lines of royalty) and/or aristocrats (the ruling elites that owned vast property).
Once countries converted into “war machines”, it became a sort of social contract between the state and the people, where the men would be conscripted into the war machine in exchange for a stake in the country’s management in the form of votes. Nation states were a way to give “peasants” or the none-ruling class a stake in the future of the country. | 3cb10b11-c34b-461e-9787-a3cc98f550f9 |
21rnb4 | Why do people hold their hand on a bible when making an oath? What if the person isn't Christian? | The "hand on the bible" gesture is purely symbolic. Meant to express that your words are all honest.
If you are not Christian, you can ask for another religious text or governmentally binding, secular text where you will be asked to perform the same gesture. | 43ffe547-b41d-457f-a688-3ca97412fe69 |
x2okx | What exactly is DDOS | its when someone denies your internet connection by clogging it up with spam.
imagine the driveway to your house. you can usually drive in and out of it fine when theres no traffic. if theres a few hundred cars of traffic on your street, its going to be hard and time consuming to get out of your driveway. DDOS is when some mean person sends those 100 cars of traffic to drive in front of your house for the sole purpose of not letting you out.
your driveway is your internet | f4e78756-570e-47b0-9e6d-09000e733c6d |
5jjpqb | Why and how does flour/dust explode? | It doesn't really explode, it burns. Explosives turn to gas almost entirely and this *new* gas causes a shockwave as it makes space for itself and pushes air away.
Flour/dust burns, because it's dispersed fine particles it causes a huge fireball where entire volume is on fire, heating up the atmosphere air already there and causing it to expand.
It burns way better in the air than while piled up, because it's surrounded by lots of air and can burn from any side.
So if there's enough combustible dust floating in the air and an ignition source appears it can start a chain reaction where flames and heat from one grain of dust ignite the other particles nearby until the entire dust cloud is on fire. | 6458850e-fadc-4994-99d0-2f4570cc580c |
4b7uph | What do websites have to gain by making their visitors annoyed (from excessive popups/poor formatting/etc) to the point that they leave and never come back? | I think you may be talking about a specific type of site. They're not actually trying to provide value and they know you'll never come back. I'll simplify the numbers here but the obtrusive ads and sheer volume of them mean they get paid 2 cents in total for the page view where you saw the ads.
They paid 1 cent (directly and indirectly) to get you to view that page (leaving aside those listicles where you have to click through to a new page to see the next item in the list). They made 1 cent (revenue less cost) on your visit.
They repeat this a million times and presto, they've got $10k profit. Rinse and repeat.
They don't bother trying to keep you there by providing value because that increases their costs significantly. Once you're at the page and the ads are loaded, the content doesn't have to be useful or interesting at all. They've made their money from you and that single pageview was all they wanted.
This is basically Web spam. There's different variations of this but this is the most basic. An arbitrage of sorts. | 8fa9d123-7d8c-459c-a005-44f932ff2fc2 |
2pjnoc | Rock and Roll is Dead. Why? | I've contemplated this question for a few weeks after recently watching Almost Famous. I think it's two things:
1. The 50s/60s/early 70s, like you're referring to, were the first years of rock. Like many things in life (Facebook, rap, college football, fast food, the internet, etc.), when they're first introduced they are a new concept without any coercion. The motivation behind the practice was driven by the ambition of the original creators and facilitators with modest monetary gains for most. This is partially what brings other people to the "scene". They enjoy the "newness" of the thing and want to explore.
2. As time goes on, market factors and influencers (money) control what can and cannot be done. Bands say yes to record contracts, the bands eventually break up, and we are left with the majority of the marketing and money behind rock with these record companies that initially used rock to build themselves up. Well, they aren't going to fold the company, instead they are going to find what "sells" and will stand behind it 100%, often influencing what is "liked" based on what they have to offer, making a shit-ton of money. It became the thing where the company dictates what we like instead of us choosing what we like. Eventually, collective tastes for music become tied to what record companies put out, and we go to those companies to seek what is "good" or "popular." We don't actually seek out these companies, this is all unknown to most people. We simply turn on the radio, visit YouTube, and download Spotify tracks because of an interview we heard with an artist, a social media campaign, etc. It's all meant to seem "organic" but it's not. Almost everything that's done to promote music today is calculated.
I do think there are people who love rock and that there are great rock bands out there with really great music. But our collective "taste" for music has been skewed so much, that I'm not sure if it will ever swing back. Because like most parts of our culture, unless there's an event that brings media attention to rock, it's won't make many waves.
I actually think the time is right for crazy, irreverent rock stars, like Jimi, the Beatles, the Stones, Stantana, etc., to bust on to our politically-correct media scene and draw all focus back to rock, just like what happened in the old ol'e days. | cc813b66-c30a-40e9-b343-e9e125a22852 |
41suoc | Different writers for Star Wars VII-IX. | The writers and Disney have worked out a basic framework for the films. All the writers and directors know how the broad strokes of the stories the films are going to tell, but the writers/directors will fill in many of the details and decide what is the best way to actually tell the story. A lot gets added and dropped over the process of making the films. J.J. Abrams didn't even have a final cut of the Force Awakens until about a month before the film was released.
In Star Wars Rebels, there is a character named Katsue. [Her design an abandoned piece of concept art for the Force Awakens](_URL_0_). | 76ffb7a5-40c8-44b3-b7aa-6aaac418f871 |
2w8cbt | what's actually happening to us when we "burnout"? | Will power is finite. It's not an unending well like some people would like you to think. For those that willpower comes easy to, they can by very dismissive of those for whom it comes very difficult.
Might take you 5 will powers to not eat that cookie. Might take someone else 50 will powers. There are things that can motivate you, or recharge your will powers battery. But over time... Over a long enough timeline, everyone can and will burn out eventually.
* Repetition (the sheer repetitive nature of most tasks can be mind numbing)
* Lack of motivation (both internal and external)
* Lack of results over the long term while others excel (If you're built in a way that you're not getting results, like stubby fingers for a piano player, shortness for a basketball player)
* The desire for change / newness. (Newness is exciting and refreshing. It can recharge us for a while until it wears off)
This phenomena basically works for everything. Careers, goals, school, fitness. | 11d39107-95bf-4f9e-b96c-3e2fbf2c21c1 |
3ie5mf | the rise and fall of KODAK, and why won't it ever be a 'giant' again | They put all of their eggs in the film basket. They even invented digital cameras (well, Steve Sasson did while working for Kodak), but because they made the money when you bought the cameras, the flash cubes, the film, AND the processing, Kodak had it very good. They saw the digital camera as their enemy (they did still make a lot of money off of the patent though). Because they didn't move their business model to go with the times (they thought they could dictate how people took pictures), it eventually ended them.
You could say they had no way to survive it anyway, but hey, maybe they could have gotten into the mobile phone business (or at least integrated with them) | a32bfc31-bfac-4b80-aa97-2006f12e839d |
2lm8bz | How does the website _URL_0_ make money? | They basically sell you to advertisers. Either they are selling your info to them (read that fine print), or they are selling access to your eyeballs to credit card companies.
> Does this jeopardize the truthfulness of your credit report since it can be a conflict of interest?
Not really. If your credit score is inaccurately high, then you won't be able to get that nice credit card deal you applied for. So they have limited incentive to lie to you. | c1b97a51-4d6b-4256-93ed-204bcd36494b |
5h1quo | How are companies going to make money from Automation when their customers are all unemployed? | Companies don't know and generally don't care: as long as automation can increase profits in the short term -- the current and next quarter -- it's a good decision and usually provides a competitive advantage.
The long term problem of having no middle class buyers is beyond the planning horizon of most companies and governments.
Until we can get our heads out of our collective asses and understand that we are rapidly approaching a post scarcity economy where only the business owners and engineers will have "good jobs" and implement a workable form of universal basic income, economies will slowly grind to a halt as the wealthy hoard capital. Economies work best when money freely flows. | dddf08d0-8261-4ec6-a11c-f537eaa250c5 |
2gtxy8 | Since a country can print its own currency indefinitely, why can't the US for example just arbitrarily pay off all its debt that way? | Yes. The more money in circulation, the less it's really worth, period. | f99969c0-f3ae-4df6-89e5-43a24a295728 |
n0ain | What are gimmicks, and why are they often considered bad? | A gimmick is something that makes something appeal better, without adding anything in general. | 8c185de5-a5bb-4c83-adbc-f3cf98117e0f |
5thea8 | Why does cooked fish irritate an allergy but sushi/sashimi does not? | There was a study done with raw vs cooked pea allergies, that found there were cases where those allergic to the raw pea were not the cooked version. It was found that cooking the pea altered the allergen enough that the patients no longer caused a reaction.
My hypothesis from this is the cooked allergen in fish is what your allergic to, and it's uncooked form your not. This would be impossible to say for 100% certian without actually testing you and ruling out any cooking material aswell. | e4789493-4503-40aa-b5b9-ec2d6da6e585 |
1rls76 | Official ELI5 Bitcoin Thread - Round II | Hi y'all! former bitcoin miner here (I'll explain what that means in a minute), and I thought I'd answer some of your inevitable questions!
First, inflation: /u/Koooooj already gave a pretty good explenation of how bitcoins prevent inflation: they're released in controled amounts that is continually halved, so that there will only ever be 21 million coins in circulation (they will most likely have to increase this number at some point, as bitcoins are inevitably lost, [see the man who threw his hard drive away](_URL_0_)). "But wait!", you may be saying, "how do they distribute the new bitcoins? Do people just randomly get them? Is the distribution of bitcoins someone's job?" The answer is: sort of. I'll answer this along with "how are bitcoins secure?", which is my area of expertise (if you can call it that).
Anyway! Yes, how are bitcoins secure? if they only exist digitally, then what is to stop someone from hacking all the bitcoins to steal them, or just shutting the system down? This is an important question. If bitcoins were even *a little bit* insecure, they would have no value. It'd be like asking people to invest in a pile of money that's left open in town square. some background: first off there is no central bitcoin server. let me say that again, **THERE IS NO *CENTRAL* BITCOIN SEVER**. All information about bitcoins is hosted on the various computers that have bitcoin wallets. Now I here you say "Hold on just a second, lprekon! Doesnt that mean it'd be even **easier** to hack, since the only information i'd have to change is on my computer to say it has more bitcoins?" Wrong my friend! This is basically how it works: Every bitcoin has it's own really long hexadecimal (base 16, using A-F in place of 10-15, meaning you can have bigger values with less numbers) code, which identifies it. Whenever you make send bitcoins somewhere, a broadcast is sent to **everyone** that says "this wallet address send these *specific* bitcoins to this wallet address." If you've ever tried to set up a bitcoin wallet and downloaded the client, you'll have noticed that before you can do anything, the client starts a really really big download. That download is the ***entire*** ledger of every bitcoin transaction, ever. That's right, ever. It updates every time you open the client. Each computer has a huge ledger detailing who has what bitcoins when, so it knows everything's legit. But the important part is that the ledger is secure and accurate, which might seem impossible without one central server, but that's where the trick comes in!
Every few hundred transactions are bundled into blocks, which is just a big list of who sent what to who. These blocks are what's sent around as part of the ledger, but they also have one addition, a special number that keeps them secure! Bitcoins entire security is based on the concept of "hashing". For those without a computer science background, you can just think of it as a weird thing computers can do with a big block of data to turn it into a really really really long number (i'll explain more in-depth if people are interested). What's unique about hashing is that it's one-way and unpredictable. There's no way (in a good hash) to figure out what the original data was from the *hash code*, and there's no way to predict what the hash code will be, other than going through the hashing process (which is long and arduous). Changing one small number in a data block will COMPLETELY change the hash code. So, what these blocks do, is the hold the hash code of the next block. If someone tries to hack the system and change the info in a block to say they haven't spend bitcoins X, Y, and Z, the new hashcode is completely different from the one held in the previous block, so everyone knows it's a fake. Now, what's to stop someone from just hashing their new block and slipping the new number into the last block? The fact that hashes are very very computationally difficult. So much so, that the creators of bitcoins can't do it themselves, which is where bitcoin miners and the distribution of bitcoins come in.
I won't go into exactly how bitcoin mining works (unless y'all want), but i'll give the overview: bitcoin mining is essentially just renting out the processing power on your computer to hash these blocks so they can be added to the universal ledger. The miners are paid, per block, in brand new bitcoins! There are hundreds of thousands of them, all across the world, lending their processing power to "mine" the blocks.
**TL;DR** bitcoins are secure because there will only be a set amount, preventing inflation, and because it's really, *really*, ***really***, ***REALLY*** hard to hack, to the point that it's simply impracticable. You'd be better off hacking your local bank than trying to steal bitcoins
**Edit**: alright, so y'all want to learn how bitcoin mining works, I'll tell you. First let me say that much like your high school science teacher, I lied for the sake of simplicity. I also don't completely know what I'm talking about (heeeyooo!) but I do have a clue. First, the basis of bitcoin mining is hashing. 'Hashing' is just turning a whole bunch of data of any sort into a single (though very large) number. For a hashing algorithm to be "good", three things must be true: 1) changes to the final number, or *hash code* should not be predictable. There should be no easier way to compute the final hash code than running the algorithm. 2) one should not be able to deduce the original data from the final hash code. 3) the results must be reproducible. hashing the same set of data multiple times should yield the exact same result. Now, for anyone who paid attention during algebra class, this might seem ridiculous! Any mathematical operation can be undone, and since you can't randomly generate numbers, how are people unable to work backwards to get the original data? The secret lies in computer logic. All the data is processed as 1's and 0's, and the computer messes around with these numbers, with no regard whatsoever for what they represent. In addition to, well, addition, as well as subtraction, division, and multiplication, computers mess with the data through bitshifts, and logic operations: AND, OR, and XOR. AND-ing two numbers together works like this: you line the bytes (collections of 1's and 0's) up, and if a certain spot is a 1 in both numbers, the new number has a 1 in that spot. other wise it's a 0. The new number has a 1 wherever the the first number had a 1, *and* the second number had a 1. When you OR two numbers, the new number contains a 1 in any spot where the first number has a 1, *or* the second number has a one. XOR is a bit weird. When you XOR two numbers together, the new number has a 1 where ever one, but not both, of the previous numbers had a 1. They work like [so](_URL_1_). A hash algorithm uses everything I've listed here to morph a huge block of arbitrary data into a nice hash code. Bitcoins use the [SHA-256 hash algorithm, developed by the NSA in 2001 and currently unbroken](_URL_3_)
Now, onto the actual mining, and the where I lied. The blocks don't actually hold the hash code of the next block. They have an arbitrary number (~~that has a name but i cannot for the life of me remember it, so we'll just call it *little number*~~ /u/Bd452 reminded me it's called a 'nonce') that is added in to the hash. The number has no connection with the actual data. What happens, is when a block is released (which is a regular occurrence, every few minutes-hours), everyone who is in the mining business races to figure out what ~~little number~~ nonce will cause the hash code to come out below a certain value. Why is it done this way? for control. The hash itself is not that hard. Most computers can do several hundred a second. adding in this little number creates a guess-and-check game that typically requires billions of hashes to get right (because the numbers are so incredibly long, there are a whole hell of a lot more possibilities **over** the target than under). Doing things this way dramatically increases (read, a billion times) the computational power needed to 'mine' each block, which makes it horribly impractical for one person or group to try to rewrite the bitcoin ledger. Like i said, if you have that kind of power, go hack a bank. It also allows those in charge of the distribution of new bitcoins to control the rate at which they're released. You see, right now, whenever one (or a group, as most mining is done in guilds, due to the huge processing power required) solves, or 'mines', a block, they're paid with 25 bitcoins. Every week (I believe) the people in charge of bitcoin (or it could just be a computer. that info wasn't relevant to my operation) looks at the number of bitcoins paid out in the last week. If it was more than expected, they drop the target number, making it harder to mine the blocks, meaning fewer are mined and less coins are paid. On the other hand, if not enough were released, they raise the target number, making it easier to mine blocks.
At this point I think I've covered everything relevant to ELI5. If you guys have questions over anything I've covered here, I direct you to the [bitcoin wiki](_URL_2_) or /r/bitcoin
**Edit 2:** please be aware guys, I havent been a miner in months, so any information I give about the profitability of bitcoin mining is at least 8 months old. The price as increased 8x since then, and I have no idea how or if the # of miners or difficulty of blocks has increased to match. It could be far less profitable, far more, or about the same, I just don't know. I will answer all your questions on this subject, just take my answers with some skepticism.
**Edit 3:** great questions guys, keep 'em coming! I'll stay and answer as long as you guys need! | 260bf6ba-e0ca-4b47-a143-5086ea67b4c4 |
35umj3 | How could humans realistically colonize a planet with modern technology (assuming that getting there isn't an issue)? | Mining tunnels seems the best option today. We can move huge drills to cut large habitation tunnels into the crust. These tunnels would provide shielding from radiation and meteorite impacts. Multiple tunnels can be combined to make large areas for food growth. | 709921f1-de19-4570-8914-681013d76ffa |
m4g1p | The eurozone crisis. Whats going on? | Greece accumulated a shit load of debt. They can't cover that debt. They need the rest of the eurozone to bail them out. Other countries(Germany) don't want to, but they share the same currency as Greece, so Greece failing would also hurt them. | 84ed3576-49dc-4f29-b8c5-a9eb81c147d5 |
2nkb6m | How are guns/bullets traceable | Guns have an individual id number stamped on them. As far as bullets go, when they are fired the barrel leaves unique markings on the shell which can be traced to the gun that fired it. This only works if the investigator has access to the offending gun and does not work for shotguns. | 7606b270-8514-4263-ac12-11aea6560375 |
3qblxh | Why are my muscles feeling sore after a poor night's sleep? | I can think of a few things that cause this.
Most importantly, your body makes a large chunk of repairs to your muscles during sleep. If your muscles are damaged (which just happens when you use them), then not sleeping well will mean your body isn't able to repair as much as it otherwise would have. Especially if you're done an intensive workout, this means you're likely going to be feeling the soreness of your muscles longer as they can't be fixed as easily.
When you sleep, your body releases chemicals to do things like relax your muscles and stop you from being able to move your muscles in your sleep (sleep paralysis). If you're woken up before these chemicals have a chance to clear out, you're likely going to not be as coordinated and can potentially feel sore from it until you "wake up".
A "bad nights sleep" may be the result of something that also causes you to be sore -- so it may not be the lack of sleep itself. Not sleeping in a good position can tense and strain your muscles. This can make you repeatedly wake up in the middle of the night, possibly making you toss and turn into worse positions. Things like dehydration can also keep you from having a good nights sleep, and dehydration itself will make you feel very sore. While you normally will get water if you're awake, you might not do that quickly enough while sleeping. | 8c0feeb0-94cc-48a3-ad4b-75e4f1694833 |
2ux0lv | Why are so many retail stores uniforms a blue shirt and khaki pants? | The khaki's represent a laid-back atmosphere to make customers feel welcome and comfortable. The color blue is meant to represent loyalty, trust and intelligence. | f847577c-961d-4718-b530-38e2f5fd818c |
4hzj0k | How Saudi Arabia, Venezuela and other oil export depending countries are dealing so differently with low oil prices. | Imagine you have several households, and all of them have one family member with a pretty decent income as salesmen (oil revenue in this metaphor). However, some of them have to commute further than others, and have other expenses that mean they get to keep less of their total pay. If sales drop low enough, it actually costs them more to sell their goods than to do nothing.
Some families deal with the problem by taking out payday loans, or second mortgages on their house. A bad long term strategy, but so long as sales eventually recover, they will probably be ok.
Some of these families have been throwing extra money into savings for years, so when sales go down, they can tap into their savings (Saudi Arabia for example). Additionally, some of these countries have been using their extra money to diversify their income sources (such as paying for other members of the family to attend college), so they are not as dependent on the sales revenue (Such as the United Arab Emirates). They can also look into selling off assets, like a second car (Saudi is looking into this option).
On the other hand, some countries spent nearly every dime as they earned it so they have no savings, and failed to perform maintenance on the car they use for their sales job, so it doesn't travel as fast anymore, which impacts their sales (Venezuela). Also, they defaulted on the loan for the car and have terrible credit, so no one wants to loan them anymore money. | 04ce7163-9007-4167-a0aa-33586edbd4d4 |
4u29vu | Why is it easier for non-native English speakers to sing, than to speak, with good pronunciation? | That's because we repeat the sounds we hear, instead of processing the sound from scratch.
Imagine speaking like drawing a horse, isn't it easier to copy one from your drawing book than drawing one from a blank piece of paper? | 6efef10d-acda-4bfb-981a-b955285fbe90 |
7w1gtn | How did presenters create slides with text and graphics in the 80's? | As a college student in the 1990's I had to do a lot of these for my courses.
There was a way to use a copier - certain brands of transparencies (clear 8.5 x 11 inch plastic) could be fed to a copier and the grapics printed on them. Our library sold the brand that worked for the Xerox copiers, back then the wrong brand would melt and jam the machine.
This was a service of professional print shops. Universities had their own in-house printing services. Large companies would have their own organic print services for all those executives making "the big presentation".
Nowadays you can either use an LCD projector, an flatscreen or just feed transparencies to your printer.
A stock joke was the "slide show" the old film slides in a mechanical carousel that were projected. Your boring relatives did this instead of harassing you on facebook. These were also used for graphics during a presentation - see old Cold War era films. | 1b7672c8-acaa-4d01-a801-d5c4f603996d |
5lu2xc | When installing updates on my computer, why am I required to close applications completely unrelated to the update? | Hard to give a more concrete explanation without an example, but it's pretty much because applications can use common resources, and you have to make sure everything stays consistent. For instance, if you're updating some video plugin, Chrome may use it. You have to close Chrome and restart it with the new version of the plugin, you can't just paws it. | 850a0f63-73d2-4c57-9906-43b2d14e3919 |
6jtm0l | Considering the amount of crap we cram into our bodies, why is urine commonly shades of yellow to brown and not purple or green? | There's a few reasons.
1) artificial dies and food colorings can't always survive the digestive tract intact, so they break down into their constituent parts, which aren't always as vibrantly colored.
2) The digestive tract may not pass the dyes into the bloodstream, so the kidneys may never have the opportunity to filter it into the urine stream.
3) Your poop can easily be multicolored. Just eat a heavily dyed cake, and see what happens 6-8bhours later. | f68d6d2f-b710-4498-89c6-efcc8da121aa |
2hconq | The anal fisting boom of 2006 | 1. Back in 2004 or '05, USC 2257 was either edited or added to the federal code. It states that any producer of pornography had to have records recording their performers' ages going back either a decade or the life of the production company. This was a big blow to porn, because they were as good at keeping records as they are at accurately portraying coitus. A lot of companies, rather than try to acquire records, just folded. A few (notably _URL_0_) disbanded and reformed under a new company name (_URL_1_). In the reforming, they probed (heh) the definition of "art" that had previously restricted whatever was shown in pornography (if it's not "art", it's "obscenity", which is illegal) and found that the definition had grown *much* more lax. Whereas before the only definition of obscenity that applied to the law was "Well, I know it when I see it", now art is seemingly defined as "Well, they say it's art, so it must be." When Insex/_URL_1_ came back, they had found so many loopholes in the obscenity laws that they were basically able to do anything - including anal fisting. Since _URL_1_ did the legwork, other California porn producers followed suit and now the pornography produced in the US is crazier than ever.
2. The internet has spoken - people like anal fisting videos. They probably would have liked them a long time ago, too, but without the internet there was very little way to track demand for particular kinks, aside from a. the weirdos who would write into porn producers to make requests and b. the amateur producers who would start their own companies.
3. Thanks to the internet, it's a LOT easier finding girls who are either curious to try such a thing, or have *already* tried it, loved it, and would love to get paid for it. Kinky Jo is an example here - she would probably engage in that activity whether she got paid or not. But thanks to the internet, she can make a nice living doing something she loves.
This likely correlates with bondage porn because of reasons 1 and 3 - _URL_1_ was one of the first companies post-2257 that made it a thing (with their perfectly-named site, "_URL_2_"), and the performers they found that enjoyed anal fisting also enjoy BDSM play. | 709e4fca-b520-4867-9014-c778dc9d7165 |
18ybfc | Why does some cheese have holes? | The answer to your question is "a big-eyed bacteria named Sherman".
First, a bit about process. If you want to make cheese - any cheese - you need the help of bacteria. When you add bacteria to milk, it makes lactic acid and gives the cheese a lot of its taste. Once that's done, a milk-clotting enzyme called rennet is added to coagulate the milk, and the cheese starts to look and feel like custard. After that, the cheese is cut into small pieces to begin the process of separating the liquid (whey) from the milk solids (curds). Large curds cooked at lower temperatures give soft cheese (like Mascarpone and Ricotta) while small curds cooked at higher temperatures give harder cheeses (like Gruyere... and Swiss).
The important bacteria in holey cheese is called *propionibacter shermani* ("Sherman" from here on in). Once Sherman is added to a cheese mixture and warmed, he forms bubbles of carbon dioxide; by the time these bubbles "pop" the cheese is already too solid to fill the newly created holes (called "eyes"). Cheesemakers can control the size of Sherman's eyes by changing the acidity, temperature, and curing time of the cheese mixture.
Sherman's peekers are controversial these days. The U.S. Department of Agriculture recently created new guidelines that regulate the "hole size" of domestically produced Swiss cheese. The scandal is that the USDA reduced the standard size of the eyes by about half, because new cheese-slicing machinery was getting caught. The Swiss aren't pleased by the revised guidelines, and insist that "Emmentaler" should have eyes as big as possible!
**edit** - so what does it all mean? That [this picture](_URL_0_) is a lot more scientifically accurate than you'd think. | f75a0024-0573-4944-aa5a-0f94aebe1ba7 |
20o6kw | Why do websites like Facebook and Youtube feel a constant need to change format? | Well that's internal information, so people who don't work at one of the companies in question can only guess. I'll take a shot at it, though.
First, just because a certain design works doesn't mean it's perfect. Everything can be improved, and Facebook and Google probably think they're doing exactly that.
Second, changing things keeps the site "fresh". Or maybe it's better to explain with a negative - they don't want things to become stagnant. There's some psychology that dictates new things are better than old things, even if the new thing isn't really any better. (See every iPhone release.)
Third, you say no one is ever satisfied with websites changing, but the reality is the *vocal people* are never satisfied with websites changing. People who are satisfied just don't say anything. The hard part is figuring out how many vocal people there are and whether they make any good points, which often they don't. (Win8 removed the start menu! We're all gonna die!)
Fourth, designers may be trying to justify their existence by coming up with "improvements" all the time. I hesitate to add this point, because I don't think it's very likely and I know some guy who hates every redesign everywhere is going to run away with it, but there's probably a few companies out there with this problem.
Now you ask why reddit hasn't changed. Most likely it's because they can't pay for it. Reddit is not a profitable company yet - they were just shy of breaking even last I heard anything - so they probably don't want to pay for anything they don't have to. Also, while they can change the layout of the site without too much trouble, adding images would take quite a bit of extra bandwidth, which is easy to translate into other costs. Looking good is expensive. | 3adf65bd-7fe2-4dd9-a2bb-c3f2f6279b8f |
6l1vtx | What is this cosmetic product really? Where does it come from? | the complex names really just come from the molecules themselves. If you're trained in organic chemistry, you can read the name and know exactly what elements and how many are in the compound. It goes a little like this (although im definitely not all the way right)
deca - 10
methyl - A carbon atom bonded to 3 Hydrogens, so 10 of these.
cyclo - arranged in a circle
penta - 5
siloxane - a molecule consisting of only single bonds (ane) of two silicon atoms bonded to an oxygen atom, so 5 of these.
A quick lookup will pull up a picture of the molecule, which is exactly as I just described.
It's just a naming system to make it easier for professional to know the properties and makeup of a compound. They're created by chemists and chemical engineers, who have studied years and know how molecules work. So if they want to keep something moist and maybe promote collagen like in make-up, they'd research it for years and come up with a chemical like the one you're curious about. Specifically, it acts an emollient, a chemical that makes the epidermis and dermis soft and plyable, AKA a moisturizer.
When people like to use "natural products" let's say like aloe, they have very similar complex compounds. In fact, all chemicals have organized naming system, even water. "Dihydrogen monoxide" is technically the name for water. From just this, someone can see its a covalent bond with two hydrogen atoms and one oxygen atom. | 0ee22ad2-d021-4f91-94d5-e3d119bc7494 |
2x5li5 | Why aren't the oceans getting saltier? | They are getting saltier. The reason we do not notice is that there is a very small percentage change even over millions of years. The dead sea is a very small body of water compared to the rest of the ocean and its relatively isolated compared to the most oceans/seas. the dead see also would not of gotten that much saltier in recent times if it was not due to the sea being evaporated in human made basins. | 91add654-7b3d-44e3-a4f9-94be176546a4 |
5k6jf9 | I'm aware of optical and auditory illusions...are there illusions for the other senses i.e. smell and taste? | There are but there probably are not as many because sight and hearing can be replicated easily (as easy as looking and listening to your computer/smartphone), while smell and taste require actual physical particles.
For taste, there is a fruit called the miracle fruit or miracle berry that after eating them, it causes sour foods to taste sweet. This is due to a chemical in the fruit called miraculin, a natural sugar substitute. Although the method is not completely known, it is suspected that the miraculin changes our sweet taste receptors to also react to sour, causing this effect.
For smell, it's possible to overload your smell senses. If you smell more than 30 different smells at once, you end up smelling the same thing as if it were a different set of 30 other smells: _URL_0_ | b38498a0-7e8d-4a95-820a-5152a47bf343 |
40kbxt | When it comes to movies/tv shows, what is the difference between directors and producers? | This can vary a lot from production to production. However, generally directors tend to be the one with the vision, on the set telling how the actors should act and how to present the story. Producers tend to be the ones making sure the tv show/film is on a reasonable budget on time, and the channel/studio/sponsors/production company are all happy with the finished project.
The Director is in essence the artist, the producer is the realist who makes sure it get's *made*.
Again, this varies depending on the director and producer involved. Steven Spielberg for instance has been a producer on many projects (everything from Back to The Future to Animaniacs) acting as a shield between the director and the studio to make sure certain risky elements are allowed into the production. Other times, producers go crazy with power and make weird demands for things that *must* be included in the film/show. | 2dd6887c-4755-4ba6-b9de-b78f8a24dca7 |
5cp24p | Does Listening to An Audiobook Affect the Brain the Same Way Reading a Book Would? | No. Reading text and processing auditory language involve separate brain structures, although many people [sub-vocalize](_URL_0_) while reading, involving both brain structures.
Another major difference is speed and comprehension. Some people comprehend text better than audio, and some the other way around. If your brain prefers text, you'll retain more information from a book. If your brain prefers audio, you'll retain more information from an audiobook. Typically, most people can read a book much faster than the narrator in an audiobook speaks, in either case.
However, both styles of reading a text have similarities as well. The way our brains visualize a scene from the text, such as when a room is being described, is identical in either case. If the room is described by a narrator, or you read the exact same description in the book, you'll imagine almost the exact same room - I say almost, because the narrator's voice can have an impact on your imagination, depending on their accent, enunciation, emphasis, and gender. | 45036f08-dd5c-4ece-82e3-2787d5dfaa48 |
4iwucq | Two objets at certanly distence. Can we put them closer each other by the half distance indefinitely? . I mean the half of the distance, then the half of that distance ......thx | Theoretically, in abstract terms yes. There will mathematically always be another half distance you can divide by.
But real world physics don't permit for this. There is a phenomenon called the Planck Unit, which I suppose you could think of as the "resolution of the universe". Much like a screen cannot show something smaller than a single pixel, the Planck unit is the smallest measure of spacetime anything can occupy. You literally cannot break spacetime into a smaller amount in real world applications. | 4fbd0fb9-931f-4be0-bece-252c7d71e6dc |
6qnqpm | What is the point of putting a video consisting of only a still image onto a Facebook page? | Hey there!
Facebook's algorithms place more 'value' on a video, and will place it higher in the feed, and is more likely to deliver it to more of the people following your page. You get more 'bang for your buck' by placing ad money in a video instead of a static image. Movement also catches people's eye, and they're more likely to pause to look at a video.
Making a still image into a looping video is a really lazy way to take advantage of that.
Source: Social Media Manager for a company. | 2f46c3dd-79b4-4fcf-abed-e13a07616284 |
7su189 | Why have Facebook, Instagram, and Twitter during the past year gone from chronological newsfeeds to “customized” newsfeeds? | [Filter bubbles](_URL_0_), by encouraging you to engage only with content you already engage with regularly, maximize engagement with their services and thus shareholder value and ad revenue.
It also "sanitizes" the content, since censoring controversial or offensive content is taken as part of the tailoring, so it's more friendly and non-controversial for advertisers.
In other words, by tailoring the content you see to be only naively what's "relevant" to you, they create a welcoming and non-challenging content environment where everything is in agreement with you and your personality profile, so you feel rewarded and comfortable in that environment, and thus spend more time in the platforms. This directly rewards them by increasing profit potential.
(In my opinion, it's a really messed up thing based on entirely misguided motivations, but our society is based on misguided incentives anyway, so it's not surprising.) | 1725b0a0-ca22-4f73-a0ff-3dc8ef4bf11a |
73ynt9 | How does the Home Owners Association (or HOA) Function? | The idea behind a HOA is to get the neighborhood working together for their own benefit. A lot of things is shared between the owners of a neighborhood such as parking spaces, sidewalks, fences or even walls and roofs. The HOA is the owners who join together to maintain these things. They also might help each other when things needs to be done, for example when it is time to paint or do maintenance on the properties it is cheaper and better to do on a larger scale. The disadvantage of a HOA is that it attracts people who want power. | d70e3cb8-8e98-49b1-a2f0-27e20306fb8d |
4u3cmm | How does Netflix make money/earn a profit off of Netflix Original TV and Films? | The same way any channel makes money by producing shows. They produce something because they want you to subscribe to their channel.
They license stuff out based on the show. They make a dvd and blu ray of the season. They sell it to syndication on cable channels. If it's not fantasy stuff like Game of Thrones they can get advertisements in the show like characters using an iPhone or something.
It's really no different from HBO, Showtime, etc. (other places that have been commercial free a long time) except Netflix isn't there on your regular T.V. when you go to channel 601 or whatever. Even that line is getting blurry. | 7f304ad2-788c-4052-a7f6-e9e5252e758a |
5ppc4e | Why do some games run on a mac but not on linux if both are unix based os. | They're not UNIX-*based*, they're UNIX-*like*. MacOS is based on FreeBSD, which i a very different operating system than Linux. Furthermore, MacOS has it's own *completely* custom GUI and graphics APIs than Linux does. Only the very, very basic components of a game would be easy to port over. | 301e4d8f-55b0-4a71-bdd2-473b9d55e09e |
mik70 | When copying files from one device to another, why does the transfer speed slowly decrease over time? | Your computer can only create and allocate files on a device just *so* fast, so if you have lots of little files there will be a lot of overhead of creating the files themselves (naming, extension, permissions, all that) on the destination drive. You will see a speed increase if you're copying larger files (compared to copying lots of small ones) as your computer doesn't have to worry about naming etc and can just focus on transferring the bits that make up the file itself.
If you are copying a large-ish file (try one at ~3-4gb) and you are seeing a definite decrease in speed first try another copying program (I use [Teracopy](_URL_0_)). Still an issue? Try copying the same file to the same device from another computer. If it is a decently stable speed the whole way using their computer your USB controller may be out of whack - try reinstalling the drivers for it. Otherwise it could very well be the cable or even the destination device itself. | 7b393e64-ea74-452b-b977-4a0d780d5f89 |
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